New designer drugs N-(1-phenylcyclohexyl)-2-ethoxyethanamine (PCEEA) and N-(1-phenylcyclohexyl)-2-methoxyethanamine (PCMEA): Studies on their metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric techniques

Studies are described on the metabolism and the toxicological detection of the phencyclidine-derived designer drugs N-(1-phenylcyclohexyl)-2-ethoxyethanamine (PCEEA) and N-(1-phenylcyclohexyl)-2-methoxyethanamine (PCMEA) in rat urine using gas chromatographic/mass spectrometric (GC/MS) techniques. The identified metabolites indicated that PCEEA and PCMEA were transformed to the same metabolites by N-dealkylation and O-dealkylation partially followed by oxidation of the resulting alcohol to the respective carboxylic acid and hydroxylation of the cyclohexyl ring at different positions and combinations of those. Finally, aromatic hydroxylation of the O-dealkylated metabolites was partially followed by hydroxylation of the cyclohexyl ring at different positions. All metabolites were partially excreted in conjugated form. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction and microwave-assisted acetylation allowed the detection of an intake of a common drug users' dose both of PCEEA and PCMEA in rat urine. Assuming similar metabolism in humans, the STA should be suitable for proof of an intake of PCEEA and PCMEA in human urine, although their differentiation is not possible due to common metabolites.     

Antibunching in the emission of a single tetrachromophoric dendritic system

The photophysics of a dendrimer containing four chromophores are investigated at the single-molecule level. First, the multichromophoric character of single dendrimers' absorption is probed by modulating the linear polarization of the excitation beam. Subsequently, using circular polarization, the same dendrimers are excited, and their fluorescence transients are recorded. Using pulsed excitation in combination with the classical Hanbury-Brown and Twiss coincidence setup the presented data demonstrate that efficient singlet-singlet annihilation ensures that always only one photon is emitted even when several excitations are generated in an individual multichromophoric molecule.     

Ein algorithmischer Zugang zu Polynomen und Splines

Zusammenfassung. Um polynomiale Kurven auf dem Computer modellieren zu k?nnen, verwendet man in der CAD-Praxis zumeist sogenannte Bézier-Kurven. Verallgemeinert man den zugeh?rigen Auswertungsalgorithmus, so kann man, auf ganz konstruktive Art auch Splinekurven definieren und ihre wesentlichen Eigenschaften auf sehr elementare Art und Weise herleiten. Der Zusammenhang wird dabei durch das sogenannte “Blossoming principle” hergestellt. Eingegangen am: 12.3.1996 / Angenommen am: 7.5.1996     

Beiträge zur Kenntnis des chromophoren Systems der Corrine. X. Über die Reaktion von Derivaten des Cobyrinsäure-heptamethylesters mit unterchloriger Säure

Contributions to the Knowledge of the Corrin Chromophore, X. Reaction of Derivatives of Cobyrinic Acid Heptamethyl Ester with Hypochlorous Acid (Cobalt)-dicyano-, chloro-cyano-, and dichloro-cobyrinic acid heptamethylesters ( 1, 2 and 3 ), respectively, as well as their 10-chloro derivatives 4, 5 and 6 react with hypochlorous acid. A report on the structure and some properties of the reaction products 8, 9 and 10 is given.     

A hydrodynamic model for profile steepening at resonance absorption

The self-consistent modification of an inhomogeneous plasma density profile near the critical layer due to the ponderomotive force of an obliquely incident p-polarized electromagnetic wave is calculated within a simple hydrodynamic plasma model.